基于改进下垂控制的储能单元控制策略研究

Research on control strategy of energy storage unit based on improved droop control

传统的直流微电网下垂控制只适用于集中式通信系统中容量相同的储能单元,并且会造成电压偏移。为了解决这些问题,文中提出了一种改进的下垂控制策略。通过引入储能单元的荷电比和容量比来设计储能单元的下垂系数,使储能单元的下垂系数与荷电状态(state of charge,SOC)和容量相对应;采用一致性算法来进行储能单元间通信,提高系统的稳定性;同时针对下垂控制带来的电压偏移采用模糊比例积分(proportional integral,PI)进行补偿。建立仿真模型,验证了改进策略与传统下垂控制相比的有效性。仿真结果表明,该控制策略可以加快荷电状态平衡,同时能够提高系统稳定性,减少母线电压偏移。

The traditional droop control of DC microgrid is only applicable to the energy storage units with the same capacity in the centralized communication system and it would cause voltage offset.To solve these problems,this paper proposed an improved droop control strategy.The droop coefficient of the energy storage unit was designed by introducing the charge ratio and capacity ratio of the energy storage unit.So the droop coefficients of the energy storage unit can correspond to the state of charge(SOC)and capacity.The consistency algorithm was adopted for communication between energy storage units to improve the stability of the system.At the same time,fuzzy PI was used to compensate the voltage offset caused by droop control.Simulation models were established to verify the effectiveness of improved strategy compared with traditional droop control.The simulation results show that the proposed control strategy can speed up the state of charge balance.The method can also improve system stability and weaken the bus voltage offset.